The question Are photons aged? and answers therein have got me thinking:
I vaguely remember hearing something about experiments where "old photons" were collected by large telescopes from very distant objects, and either their energies or their frequencies were compared to their wavelengths to c...
The air molecules move very fast and they move randomly in all directions, so their motion averages out. This means the pressure of the air remains constant despite all this motion.
Magnetohydrodynamics (MHD; also magneto-fluid dynamics or hydromagnetics) is the study of the magnetic properties and behaviour of electrically conducting fluids. Examples of such magnetofluids include plasmas, liquid metals, salt water, and electrolytes. The word "magnetohydrodynamics" is derived from magneto- meaning magnetic field, hydro- meaning water, and dynamics meaning movement. The field of MHD was initiated by Hannes Alfvén, for which he received the Nobel Prize in Physics in 1970.
The fundamental concept behind MHD is that magnetic fields can induce currents in a moving conductive...
You need to start by considering the microscopic origin of the frictional force.
In most circumstances surfaces are rough so when to touch two surfaces together they actually only make contact at the highest points on the surfaces. We call these high points asperities, and in the diagram below I...
But in things like brake disks the surfaces slide over each other and smooth each other out so the disk surface ends up very smooth and adhesion is the main source of the friction.
When the surfaces slide over each other the contact points between the two surfaces are continually being torn apart, and when this happens the broken surfaces vibrate.
It's like snapping a rubber band - when the band snaps the two halves bounce back and waggle around.
@JohnRennie Sir is it possible to study Tensors without Linear Algebra. I'm needing Tensors for Fluid Mechanics but it seems that for Tensor Analysis I have to complete Linear Algebra first. Can I do it without LA?
There's a difference between being able to use tensors and having an in depth understanding of them. You need tensor analysis for the latter but not for the former.
@Knight I wouldn't try to learn about tensors. Learn about whatever it is that you're trying to learn and when you encounter a tensor try and figure out what the tensor does. Tensors are very simple beasts. They just convert a vector to another vector.
Inspector Clouseau was French, someone asked him about the bomb blast that took place in his city, “Inspector What kind of bomb it was”, Clouseau replied calmly “the explosive kind”.
The question Are the stars distributed in uniform distribution, on the celestial dome, with respect to brightness? brings to mind a different study that I vaguely remember hearing about a while ago, perhaps several decades. This is a summary of how I recall it, it may not be 100% accurate:
An as...
@Knight why did they call the pink panther, "pink"?
> The first film in the series derives its name from the eponymous pink diamond that has an enormous size and value. The diamond is called the "Pink Panther" because the flaw at its center, when viewed closely, is said to resemble a leaping pink panther.
@Korra the wavefunction encodes all the information about the particle. We get the observables like momentum by applying an operator to the wavefunction. The wavefunction itself is not observable.
Every once in a while, we get a question asking for a book or other educational reference on a particular topic at a particular level. This is a meta-question that collects all those links together. If you're looking for book recommendations, this is probably the place to start.
All the question...
Is it possible that the reason human brains learn so fast is that they already have genetically embedded concepts of the ideas? For example, if you show a baby a car for the first time, it will really quickly build a mental image of it and can recognize it, while a neural network needs tons of data. Why is that?
I heard Ian Goodfellow saying in an interview that one of the AI's problems right now is that they need a lot of data to learn, while a baby brain learns faster, something like that.
@JohnRennie Sir I’m learning Green’s Theorem. My book writes $$ \mathbf A = U \nabla V - V \nabla U $$ and , consequently, for $A_n$ $$ A_n = U \frac{\partial V}{\partial n} - V \frac{\partial U}{\partial n}$$
I'm unable to understand how he got that fornula for A_n
"It turns out that humans use a wealth of background knowledge whenever we take on a new game. And this makes the games significantly easier to play. But faced with games that make no use of this knowledge, humans flounder, whereas machines plod along in exactly the same way."
If I had to guess, I'd say that AI learns no faster or slower than a human baby but the human baby has prior experience and connections from which to build new stuff...
This is a list of primate species by estimated global population. This list is not comprehensive, as not all primates have had their numbers quantified.
== See also ==
Lists of organisms by population
Lists of mammals by population
The World's 25 Most Endangered Primates
== References... ==
What are your opinions about what the future of AI will be? Do you think robots will eat us, make batteries out of us or maybe we'll live in harmony? Or maybe we'll transcend to a higher state of existence?
@skullpatrol Pal whether you believe it or not but today you were a little different I found you different today. I don’t know, it may be with me or who knows!
I have a question about my Physics Stack Exchange post: How to exactly evaluate the Magnetic Field associated with the given Electric Field in a lossy medium?
My question here is that instead of just down-voting my question that i just posted, shouldn't the same person explain why, especiall...
@SirCumference I've always assumed it's because someone has a twisted fetish with watching me struggle to write the symbol properly without it just turning into random curls that look nothing like it.
After many years as a colloid scientist studying zeta potentials I can still not reliably remember the difference between zeta and xi, nor draw either one of them. My life has been a failure.
Slereah I think French and German languages are not much different from Greek and Latin and therefore those writers use these symbols very much. When we the original works of Fourier it becomes extremely hard to whether he has made some symbols or some insect has died and got printed.
@JohnRennie I don't know if I've ever considered much difference between those two symbols. I can't think of many contexts where I had to use xi and zeta at the same time. I think my brain just internalized them both as "hard to draw scribbles".
@Knight French as a Romance language is much closer to Latin and Greek than German is, but language relationship does not explain why one would tend to use Greek letters (the Romans certainly didn't think they had to use Greek letters!). The explanation is more likely that most early European scientists had a "classical" education that involved Greek, so when they needed symbols, they turned to what they already knew.
@ACuriousMind Yes, English always considered themselves to be different from all Europe and therefore they adopted English alphabets for variables while the rest of Europe went for Latin and Greeks.
@AaronStevens You said in your comment that intolerance is due to being off-topic not something inborn, my argument is in my first paragraph I made it clear enough that Homework problems are off-topic and then in next para I said some people have intolerance with it, isn’t it natural to assume that intolerance is there because it is being off topic?
@Knight Ok, that is fine and you can address that to me. I am asking if there is anything I can do to help with the annoyance you have had with me lately. I am fine with having a discussion, but you seemed quite annoyed about it. I just want to know what I can do to help.
@AaronStevens No, I’m not annoyed with you. We just come to same platform for a few hours and even in that if I were to hold some grudge against you then I think I’m not a good social man. You got any problems with me? If my words have hurt you ever I publicly apologise you for that
@Knight I was not part of that conversation, and I don't know what you are talking about. Yes JMac and I tend to get along here, but that doesn't mean I know everything he has said, nor does it mean I agree with everything he says or that I think exactly like he does
So I don't think it is fair to base your reactions to me on how you view JMac or interactions you have with him
@AaronStevens Yeah, I shouldn’t judge you by the acts that he did. But you know you people are very powerful, your duo is nice and after all ACM is with you. So, sometimes I become quite aggressive but ... um... let’s go on as we have
@Knight I try not to use any power I may have extensively here. Especially by just commenting on your post for something I thought was unclear. The point of writing posts is for other people. So if a point is not clear to others but clear to you, then telling others they should see the point you are making isn't going to help your post be taken correctly by others
@AaronStevens Aaron problem is that when we discuss something your friend and other people come and starts taking your side and then it feels like trolling. You see you post it many times “I agree with JMac” don’t you think posting that is a little not nice
@Knight Stating my agreement with someone is not trolling. Multiple people not agreeing with you is also not trolling. And that didn't even happen in this case
@AaronStevens Ah! I’m not saying that, I’m saying it feels like trolling when you write “I’m with JMac”, why you need to write it you can just upvote his comment and “1” will make it clear that one more person share that view
@Knight Usually I supplement comments like that with some supplementary information, my own additional thoughts, etc. I do only up vote comments if I think they have said all that needs to be said.
@ACuriousMind Actually, I came here in month of November 2019 and I and Aaron were discussing something friendly then JMac came and started saying to me “you’re not clear” , “you’re not clear”
@Knight I am fine with having a discussion about your post. If you think you have sufficiently addressed the point I bring up in my comment that is fine. You can let me know that. If I then agree, then that is it. If not, then I can help suggest ways to make the post clearer. Then we both win.
@AaronStevens yes. Did I satisfy you with my clarification of that?
@ACuriousMind My comments from that Meta post were deleted, I posted something about John sir and G.Smith sir. Can you please tell me why they got deleted? As knowing it would help me in not doing those things again.
@Knight They did not add information related to the topic of the post, nor were they aimed at criticizing or improving it. Additionally, naming specific users that might help another user is not something we do here - if someone wants to volunteer to help someone, let them do it on their own.
@ACuriousMind Okay, shouldn’t I do that for new contributors? Is taking the names of specific users makes a burden on them to help the OP even he doesn’t? Am I right
@Knight Yes, naming specific users might create an expectation on the part of the OP. And the users you name have never agreed to that, so don't do that. (Additionally, this doesn't scale well - just imagine one user being inundated with dozens of request for help of the "this other user said you'd help me" kind)
@Knight FYI, that's a pretty poor paraphrase of the conversation we had yesterday. I was talking about US politics and elections being weird. That is not the same as calling Americans weird. I was born and raised in suburban Canada. Culturally, Americans aren't weird to me; we have a lot in common. Just their election process and the results of it seem pretty weird, even on a global scale.